\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(270:1.5){A}
    \tkzDefLine[perpendicular=through A,normed](O,A)  \tkzGetPoint{b}
    \tkzDefPointOnLine[pos=2.0](A,b)  \tkzGetPoint{B}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawPoint(O)
    \tkzDrawSegment(O,A)
    \tkzDrawLine[add=0 and 1](B,A)
    \tkzMarkRightAngle[size=.2](O,A,B)
    \tkzLabelPoints[above](O)
    \tkzLabelPoints[below](A)
    \tkzLabelSegment[pos=1, right](A,B){$l$}
\end{tikzpicture}

